This application is for the Gynecologic Oncology Group (GOG) CCOP Research Base. The Gynecologic Oncology Group is the premier clinical trial group in treatment of gynecologic cancers and has developed an active cancer prevention and control program. The composition of the Gynecologic Oncology Group includes gynecologic oncologists, medical oncologists, radiation oncologists, pathologists, nurse oncologists, biostatisticians, laboratory scientists, behavioral scientists, epidemiologists and other disciplines. The GOG is strengthened by an affiliate network of community-based investigative teams led by gynecologic oncologists. This network consists of small university and/or large community hospitals and should serve as a significant supplement in the prevention program by augmenting contributions from existing and new CCOP organizations in providing enhanced opportunities for recruitment and enrollment of patients into cancer prevention trials. The CCOP institutions formed along the lines of typical multi-site medical oncology cooperative groups will find opportunities to enter patients into treatment and prevention trials developed by the GOG. However, many of the future prevention studies will require access to patient groups previously not seen in CCOP institutions. As they adjust to these new challenges, the affiliate network already in place in the GOG will provide support and leadership in making the prevention program successful. In previous experiences as a Research Base, the GOG's CCOP institutions have met treatment goals. The GOG lost its Research Base status due to failure of the CCOPs to meet prevention goals. The combination of CCOP and Prevention Member Gynecologic Oncology Affiliate institutions should correct that previous deficit. Patient Accrual: Under the previous Research Base funding, patient accrual to treatment trials was satisfactory for each year of the grant - 1997 through 1999. In terms of prevention, the CCOP institutions did not meet the standards provided. While that experience showed that the requirements of the GOG in terms of cancer prevention studies may be different from those developed by other Research Bases, it also showed that there were CCOP organizations that could meet the challenge. The time requirement for adjustment was longer than anticipated. However, there is a provision in the current RFA allowing the designation of members of the cooperative clinical trial organization as Prevention Members.